Microgravity-induced muscle atrophy in rodent and human models

Area of Science:

• Space biology
• Skeletal muscle physiology
• Cellular biology

Background:

• Spaceflight induces significant skeletal muscle atrophy, particularly affecting postural muscles.
• This leads to reduced muscle mass, cross-sectional area, and contractile force.
• Countermeasures like exercise show limited success in preventing spaceflight-induced muscle loss.

Purpose of the Study:

• To review and compare microgravity's effects on skeletal muscle atrophy in rodent, human, and in vitro models.
• To highlight species-specific differences in muscle response to microgravity.
• To evaluate the role of Reactive Oxygen Species (ROS) in spaceflight-induced muscle degradation.

Main Methods:

• Review of existing literature on microgravity and skeletal muscle atrophy.
• Comparative analysis of rodent and human physiological and cellular responses.
• Examination of molecular adaptations, including mitochondrial function and oxidative stress.

Main Results:

• Rodents show rapid atrophy, mainly in slow-twitch fibers; humans exhibit greater variability affecting both fiber types.
• Microgravity triggers mitochondrial dysfunction, oxidative stress, and impaired synaptogenesis.
• Reactive Oxygen Species (ROS) play a significant role in muscle loss during spaceflight.

Conclusions:

• Microgravity-induced skeletal muscle atrophy presents a complex challenge with species-specific responses.
• Mitochondrial dysfunction and oxidative stress are critical cellular mechanisms.
• Further research into ROS-mediated pathways is essential for developing effective therapeutics for astronauts.